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McGraw Hill Financial, Inc. is an American publicly traded corporation headquartered in Rockefeller Center in New York City. Its primary areas of business are financial, publishing, and business services.
A superclass of Protozoa (in the subphylum Sarcomastigophora) in which movement involves protoplasmic flow, often with recognizable pseudopodia. Gametes may be flagellated, as in certain Foraminiferida. Most species are floating or creeping; a few, sessile. The pellicle is thin, and the body is apt to be plastic unless restrained by skeletal structures. Sarcodina live in fresh, brackish, or salt waters; soil or sand; and as endoparasites in animals and plants. A group may be limited to a specific habitat, but many have a rather wide range.
Industry:Science
A superclass of the Protozoa also known as the Flagellata. The flagellates make up a large and heterogeneous group of Protozoa, varying in size from <i>Noctiluca</i>, 1500 micrometers in diameter, to monads, barely 3 micrometers long. The common morphological flagellate type is spherical to cylindrical on an anteroposterior axis. They are probably more nearly representative of the primitive protozoan type than Sarcodina or Ciliophora, but exhibit a more evident relationship to the former. Despite their common morphological plan, based on the flagellum as a means of locomotion, Flagellata are very diverse in shape, colony formation, internal structure, external shell or test, color, physiology, reproduction, and choice of environment.
Industry:Science
A superclass of the subphylum Vertebrata (Craniata). Gnathostomes are animals with jaws, involving a vertical biting that developed from modified gill arches. They are further characterized by a notochord (an elongated dorsal cord of cells that is the primitive axial skeleton in all chordates) that is present in the ontogeny of all lineages but replaced by vertebral centra (the main bodies of vertebrae) in most taxa; early fossil forms with a bony exoskeleton that was lost in the higher lineages; limb girdles (secondarily lost in some forms) supporting paired appendages in all but the most primitive taxa; myelinated neurons; an adaptive immune system; intrinsic eye muscles; a sperm duct linked to the urinary system; and a distinct cerebellum. Some of the characters were carried over from the primitive superclass Agnatha, but jaws and paired appendages are unique to Gnathostomata.
Industry:Science
A supernova is a brilliant cosmic explosion marking the violent death of a star. These explosions are extremely bright, and in its final blaze of glory, the death of a single star can outshine the combined light from the billions of other stars in its home galaxy. One recent supernova, named SN 2006gy, surprised astronomers because it was intrinsically much brighter than any previous explosion, and it lasted much longer as well. The tremendous amount of total energy released in the visual light of the explosion exceeded other supernovae by a factor of 100 or more, and traditional explanations of supernova power sources seem inadequate. (Astronomers use a simple naming scheme for supernovae, with SN and the year of explosion. The year is followed by a letter or two in order of discovery, starting with A through Z, then aa, ab, ac, …, ba, bb, bc, and so on.)
Industry:Science
A superorder of Echinoidea, subclass Euechinoidea. These invertebrates are characterized by having a rigid, exocyclic test and a lantern or jaw apparatus developed sometime during the life history and usually persisting into the adult stage. The included orders are the Clypeasteroida, Cassiduloida, Neolampadoida, and Oligopygoida.
Industry:Science
A superorder of Euechinoidea, having a rigid test, the periproct within the apical system, keeled teeth, a complete perignathic girdle, and branchial slits. J. Durham and R. Melville (1957) include five orders in this group. There were formerly distributed among the Stirodonta and Camarodonta in the classification of R. Jackson (1912).
Industry:Science
A superorder of the molluscan subclass Pulmonata containing about 2500 species that are grouped into 11–15 families. Only a few members of the family Ellobiidae are terrestrial, with the other species today being tidal to supratidal or estuarine in habitat. The families Siphonariidae and Trimusculidae are marine limpets with caplike shells. The families Otinidae and Amphibolidae also are marine taxa.
The remaining families inhabit a great variety of fresh-water situations and are quite varied in shell structure and shape. Because of this great variation in habitat and form, it is difficult to find structures that are common to all taxa and thus diagnostic of the group, which indeed may not have a common origin. The most easily observable characters are having the eyespots normally located at the base of two slender tentacles that are neither contractile nor retractile, and usually having two external genital orifices. Most features of the anatomy are shared with other pulmonate superorders, or are specializations related to major changes in habitat or body form.
Industry:Science
A superorder of the subclass Euechinoidea comprising primitive irregular sea urchins (Echinoidea) that have simple, undifferentiated tube feet and tuberculation and that retain a high degree of radial symmetry. They have a fully formed functioning lantern when juvenile, and they retain it throughout life. Eognathostomata comprises two orders, Pygasteroida and Holectypoida. Pygasteroids have a large, centrally positioned mouth; the apical disc has only four genital plates, the posterior plate having been lost. The periproct is aboral and lies in the posterior interambulacrum, either abutting the posterior margin of the apical disc (Pygasteridae) or separated by a relatively small number of interambulacral plates (Anorthopygidae). Holectypoids resemble pygasteroids, except that their periproct lies on the oral surface close to the peristome. They also have a compact apical disc in which there are five genital plates; the posterior genital plate may or may not be perforated by a gonopore.
Industry:Science
A supraorder of extinct marine reptiles from the Mesozoic, or the Age of Dinosaurs, belonging to the subclass Diapsida. The group consists of the order Ichthyosauria and several basal forms from the Early Triassic.
Industry:Science
A surface ship designed primarily for use in warfare, either to operate in direct combat or to provide support to other ships engaged therein. Naval ships can therefore be categorized as either combatants or noncombatants (auxiliaries), both with unique design characteristics.
Industry:Science
